The present invention relates to the surgical replacement of diseased or damaged joints of the human body.
A wide variety of prosthetic devices are presently available for surgically replacing the diseased or damaged joints of the human body. Such prosthetic devices, for example, are used to replace defective finger joints, elbow joints, knee joints and hip joints. Typically, these devices include an elongated stem which is inserted into the intramedullary canal of the bone adjacent the resected joint. Some of these prostheses are fixed to an adjacent bone with a cement material.
In the total replacement of a hip joint, for example, the hip joint of the patient is exposed and the femoral head is separated from the acetabulum of the pelvis. An acetabular component is affixed to the prepared acetabulum. The femur head is surgically removed and the top of the femur and intramedullary canal are prepared for receipt of a femoral component. A cement material is inserted into the open femur canal and the stem of the femoral component is driven into the canal. The femoral component is typically fabricated from a hardened, biologically acceptable metal material such as a cobalt:chromium alloy. The stem of the prosthesis is typically fixed to the femur with a curable acrylic polymer cement such as polymethylmethacrylate. In fact, the advent of such acrylic cements for fixation of implants to the bone have made possible such newer methods for total joint replacement. Examples of such prosthetic devices may be found in U.S. Pat. No. 3,744,061, entitled ARTIFICIAL HIP JOINT AND METHOD OF IMPLANTING IN A PATIENT, issued on July 10, 1973 to Frost; U.S. Pat. No. 3,793,650, entitled PROSTHETIC BONE JOINT HAVING A SPACER DEVICE, issued on Feb. 26, 1974 to Ling et al; and U.S. Pat. No. 3,866,248, entitled CEMENT RESTRICTOR FOR TOTAL HIP OPERATION, issued on Feb. 18, 1975 to Kummer.
Various problems have been experienced with employment of a bone cement for fixation of the stem of a prosthesis to the bone. Some of these problems are particularly acute with respect to affixation to long bones such as the femur during total hip replacement. These problems are primarily related to limitation of the cement to the area of the stem of the prosthesis within the open canal of the bone. The cement may travel beyond the area of affixation in a long bone. Proper fixation of the prosthesis to the bone may not be accomplished without taking steps to limit the travel of the cement.
An approach which has heretofore been taken to prevent or alleviate the problem of cement travel involves the injection of a quantity of cement within the bone at the lowest point of affixation. The cement is allowed to cure in order to form a plug or bolus of cement prior to insertion of the rest of the cement used for fixing the stem of the implant to the bone. This method may not be fully acceptable due to the delay necessitated for proper curing of the cement plug, problems related to the adequacy of the seal formed by the plug and problems with insertion of an adequate quantity of cement at the correct location. Also, the cement plug may travel down the bone prior to curing or it may be extruded out of the bone.